THAT curling gold serpent on the background of TIME'S cover this week is the symbol of the American Medical Association and of Aesculapius, the god of medicine. It is not to be confused with the more familiar two coiled snakes that the U.S. Army Medical Corps uses, and which the A.M.A. considers a mistake. Two snakes coiled around a winged staff form the caduceus of the god Mercury, who, aside from being the messenger of the gods, is also god of commerce, the deity of thieves and conductor of the dead to the underworld. The A.M.A. prefers its own fellow, Aesculapius, who restored a dead man to life and had a daughter, Hygeia, the goddess of health. Why the serpent in either case? Because the snake in mythology was the symbol of renewal and regeneration, probably because it shed its skin each year.

IN this week's SCIENCE section appears a story on a subject that is just beginning to make a public impact, though TIME first reported on the "neutron bomb" back in November 1959. It is one of those subjects that, in the nature of national security, inevitably involves a high degree of classified information. Those who know most about it can't and won't talk. Those who do talk about it often know too little, and misinformation and exaggeration spread.

Science Editor Jonathan Norton Leonard concluded that, without giving away any security secrets, it should be possible to report what is going on in a field so potentially important to the nation's defense, so far-reaching in theory and so costly in practice. He spent several days last week in Washington, asking not for classified material but for "information that the public should have and know." His informants included members of the congressional Joint Committee on Atomic Energy, key "scientific types" in the Administration, the Pentagon and the Atomic Energy Commission.

The ground rules followed, which are the same for many TIME stories, are that some authorities talked off the record, a few allowed selected remarks to be quoted, and others talked on a not-for-attribution basis. This procedure is at the heart of TIME'S newsgathering methods, and the result in this case is a fine science story that tells all that can, and perhaps should, be told at this moment.

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